From	Michael E. Mann	Date	Mon, 10 Jul 2000 13:37:30 -0400
To	Frank Oldfield
CC	ray bradley, Jonathan T. Overpeck, Keith Alverson, Keith Briffa, pedersen@eos.ubc.ca, Malcolm K. Hughes, whitlock@oregon.uoregon.edu
Subject	Re: the ghost of futures past
Thanks Frank, My apologies... Sorry, no, I hadn't looked in detail at your original email to Ray, only his response, and simply wanted to note that others have already jumped on this bandwagon, so Ray deserves neither all the blame, nor all the glory, depending on your perspective :) And, as I stated, IPCC clearly considers such a plot not appropriate for prime time--so you won't see anything like this in the TAR. WHat I find most useful, howevever, along the lines of what you discuss, is using empirical reconstructions as a baseline for comparison against model simulations of both free and forced variability. A number of studies have attempted this recently, and the results are encouraging from the point of view that (a) the coupled models appear to be getting the internal variability of mean global/hemispheric temperatures about right [this leads us in the direction of having greater faith in future scenarios from such models] and (b) the models,forced with paleoestimates of past volcanic, solar, and GHG radiative forcings, appear to be able to explain more than 50% of the variance in the paleo temperature reconstructions. A paper to appear in this Friday's "Science" by Tom Crowley describes some impressive results along these lines. It is agreed that hydrological change and regional temperature anomalies superimposed on any large-scale temperature changes are of key importance from any practical point of view. And I think this is what we're all working towards, more regionally detailed reconstructions of climate fields (temperature, drought, slp, etc.) in past centuries. Clearly more high-resolution proxy evidence is necessary, in both time and space. I make many of these very points in a "Perspectives" article also to appear in Science on Friday, accompanying Tom Crowley's article. Will appreciate any comments on it. Hope the above provides some clarification. cheers, mike At 06:59 PM 7/10/00 +0200, you wrote: >Hi Mike, > >Not sure if your reply implied you were taking my points seriously or not - >I'm not even sure if Ray sent them on to you or you just received his >reply! My reactions to the graphs on the website are that the temperature >one does not address my points (but it does not aim to and I fully agree >that if the projections are sufficiently reliable it hardly needs to!), >that P/E is likely to be much more important than temperature per se and >that the historical sea-level curve is not really acceptable - very much >more high resolution work needs to be done on that before we have any real >sense of past variability on decadal to century timescales. > >Cheers, > >Frank > >____________________________________________ >Frank Oldfield > >Executive Director >PAGES IPO >Barenplatz 2 >CH-3011 Bern, Switzerland > >e-mail: frank.oldfield@pages.unibe.ch > >Phone: +41 31 312 3133; Fax: +41 31 312 3168 >http://www.pages.unibe.ch/pages.html > > > >At 06:59 PM 7/10/00 +0200, Frank Oldfield wrote: >Hi Mike, > >Not sure if your reply implied you were taking my points seriously or not - >I'm not even sure if Ray sent them on to you or you just received his >reply! My reactions to the graphs on the website are that the temperature >one does not address my points (but it does not aim to and I fully agree >that if the projections are sufficiently reliable it hardly needs to!), >that P/E is likely to be much more important than temperature per se and >that the historical sea-level curve is not really acceptable - very much >more high resolution work needs to be done on that before we have any real >sense of past variability on decadal to century timescales. > >Cheers, > >Frank > >____________________________________________ >Frank Oldfield > >Executive Director >PAGES IPO >Barenplatz 2 >CH-3011 Bern, Switzerland > >e-mail: frank.oldfield@pages.unibe.ch > >Phone: +41 31 312 3133; Fax: +41 31 312 3168 >http://www.pages.unibe.ch/pages.html > > > > _______________________________________________________________________ Professor Michael E. Mann Department of Environmental Sciences, Clark Hall University of Virginia Charlottesville, VA 22903 _______________________________________________________________________ e-mail: mann@virginia.edu Phone: (804) 924-7770 FAX: (804) 982-2137 http://www.evsc.virginia.edu/faculty/people/mann.html